I need a backup drive for a 13" (non-retina) i5 Macbook Pro and having read some threads on the subject (this one among others) there seems to be quite a few pitfalls to avoid. A few thoughts: Firewire or USB 3? Firewire would be compatible with my Mac Pro as well, but USB 3 would work with all PCs too (also USB-2 equipped ones at a lower speed) and I understand it's a lot faster than Firewire. Correct? MSDOS format: in case my Powerbook dies while on the road it would be nice to access my files on another computer, which could be someone else's PC or Mac, and since Macs work with MDOS formatted drives but PCs won't work with Mac formatted drives the choice is easy. But according to one poster in the above linked forum thread you should never back up to a DOS formatted drive when using a Mac as it's unreliable. Bus-powered: I've never had problems with my bus-powered drives (used with a Powerbook G4) when using Firewire, but with USB 2 I've experienced not getting enough power to spin up the drive properly. Can I get the same problem with USB 3? I prefer bus-powered drives for less hassle than bringing along an additional power-brick and cable. What brand drive should I go for? According to the above discussion many manufacturers (Western Digital among others) force users to install special drivers or software, and also won't allow other drive mechanisms to be used with their enclosures. Is there any truth to this? I do actually have a Glyph and G-Tech Mini drive which were used with my Powerbook, and both have Firewire 800/USB 2, but they're too small now. A bare drive mechanism doesn't cost much less than a complete external drive, and the drives still don't sport USB 3, so I might just as well get a new external drive. So, what would you suggest I get? I see well known brands such as Western Digital, Seagate and Toshiba all make bus-powered drives which seem suitable for the task, but like I said it doesn't seem to be just a matter of chosing a suitably sized drive and the interface of your choice any longer.